This invention relates to an access door adapted to be installed on a building ceiling or wall for facilitating inspection and/or repair of facilities such as wiring, piping and air ducts installed within the building ceiling or wall.
When the access door is designed to be installed in a building ceiling, for example, the access door includes an outer framework adapted to be fitted in a rough opening formed in the ceiling and secured to the ceiling, a cover pivotally connected to the outer framework by means of link hinges for opening and closing the opening in the outer framework, and lock means for locking the cover to the outer framework to hold the cover in the closed position.
In an access door having the above-mentioned construction, the cover is pivotally connected to the outer framework by means of invisible hinges or concealed spring hinges or through the intermediary of a rotary shaft by means of hinges.
However, when invisible or concealed spring hinges are employed in the access door, since the hinges are secured to the outer framework and cover by means of screws so that the pins of the hinges will be positioned outside of the outer framework, portions of the concealed spring hinges tend to make contact with wiring, piping, air ducts and the like facilities positioned within the ceiling, that is between the floor of one building story and the ceiling of the story positioned right below the first-mentioned story to interfere with the cover in the opening and closing movement thereof. This could lead to the occurrence of fire due to electric leakage. On the other hand, when rotary shafts are employed in the access door, a clearance is provided between the outer framework and cover so that the cover may rotate for the opening and closing operation, and a recess is formed in the inner surface of the outer framework so that the cover may be raised above the lower end of the outer framework or the plane of the ceiling.
As the result, a conventional access doors have encountered difficulties in the provision of an air-tight arrangement employing an air-tight seal member or members between the outer framework and cover and an arrangement in which the peripheral edge of the opening in the outer framework is covered by the peripheral edge of the cover to thereby preclude the clearance defined between the outer framework and cover from being exposed.